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    <script>
        /*
            自增：
                在自身基础上+1
                a++ 的值是自增之前的值
                ++a 的值是自增后的值

        */

        var a=0;
        a++;
        console.log(a);
        console.log(a++);
        var b=1;
        console.log(++b);

        var c = 20;
        var result = c++ + ++c + c;//20 + 22 + 22
        console.log(result);

        //10 11 12 12 20 19 18 18
    </script>
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